LED Projector Lamp V.2.0

Introduction: LED Projector Lamp V.2.0

About: I am a graphic designer with many hobbies. I love electronics, computers, LEDs and all things tech.
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For those of you who stumble upon this instructable, a bit of history is mandatory in order to better understand my goals with this LED projector lamp. Therefore I recommend you first read the LED Projector Lamp v.1.0 instructable I posted a while ago. Check back when you’re done for this second part of my adventure.

For this version of the projector lamp I knew I had to find a way to at least double the amount of light on the projection screen. As high-power LED’s are very expensive parts around here (I live in Sibiu, Romania) I wanted to try making my own LED array. I chose the NS6W183T LEDs from Nichia. For those of you who don’t know, Nichia is a Japanese company that produces high quality LEDs and were the first to invent the high power blue and white LEDs back in the 90’s. These LEDs were available around here and the light output was tempting.

This instructable is not yet finished. Also the timeframe on this project is unspecified. I'm publishing its progress because I need other user's opinion on some matters in order to finish it. If you think you have something truly valuable to add to this project, be my guest and share you opinion in comments. I'll try to answer them all.

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Step 1: Bill of Materials

My choice for the NS6W183T LEDs was based mainly on the light output & size. These are SMD components and for their size they put out an amazing 245 lumens each (when powered with If=700mA). I had to settle for an array of 9 LEDs, mainly because of the price involved. My hobby budget is very limited. Even so I paid about 55 Euro or 66 USD on these LEDs. Expensive for Romania, cheap for everyone else. The main goal is filling the entire projector condenser lens with light and the array does just that. There’s a problem though. The SMD LEDs I got have the light beam spread at 120 degrees. I had no choice but to go with that, in hoping that I’ll find a way to focus this light somehow.

The cooler selected (see the Cooling step) was 87 RON, that’s 24.5 Euro or 25.5 USD. I got this one because no matter the outcome of this lamp project I’ll still have a future use for it. The rest are scavenged parts, not really worth mentioning. People in the DIY community knows the importance of dumpster dives.

Final cost of materials so far is around 100 Euro, give or take. One more failed project and I’ll get to hear my wife saying “you know, you could have bought that original lamp already, given the already spent amounts”. Now that’s what I call painful irony.

Step 2: Making the LED Array

The array was made as compact as possible so as to avoid having a too dispersed light generating area. That’s because all the projectors light originates in a single point. With arrays you get several and the challenge is to focus them all in one spot. I will deal with this later, for now it’s a long way until then.

The 9 NS6W183T LEDs are arranged in series, on a custom made PCB board that’s 3x3cm. The LEDs are soldered in the center of this board, inside a 2x2cm square. I could have made it smaller but I can’t solder SMD components using reflow soldering, all had to be done by hand using a soldering iron. Each Led was checked for polarity, glued on the board using Arctic Silver Thermal Compound glue and soldered quickly and carefully. You don’t want to cook the LEDs too much, they are so fragile when it comes to temperatures. My goal is to transfer the LED-generated heat to the PCB and then further to the cooler behind the plate. Four screws will hold the PCB onto the cooler thus avoiding PCB warpage and thermal paste will be used in between the PCB and the cooler.

After all the LEDs were soldered on the board, a quick power check ( a few seconds) proved the array was operating properly and the light output was huge. If you make the mistake of looking into the LEDs (like I did) I guarantee you’ll see nine dots of light for a long time. Hopefully I’ll make good use of this very uniform light.

Step 3: Numbers

9 LEDs like the one I’m using will require 700mA at 31.5V for a total amount of 22.05 Watts of consumed power. Under these parameters I should be getting at least 2025 lumens. Provided I can keep the LEDs temperature under 70 degree (Celsius) I could then try and power them at 800mA and then I’ll be getting 2340 lumens. I assume the light losses inside the projector will cut this output in half. My goal is to use this projector in its original eco-mode, when the lamp output was only 1000 lumens. Hopefully, I’ll now get closer to that than the last time I tried. I’ll be using the same power supply I was using for the lamp v.1.0, it’s a 700mA constant current power supply. It outputs up to about 30V so I will be close to its maximum rated power output. Checking with a multimeter, the current was indeed steady at 700mA but the voltage was only 29.2V. Good enough for initial tests.

Step 4: Cooling

Another concern is the dissipated power, each LED is rated at 3.2W of dissipated power. That sums up to 28.8 Watts of heat I need to get rid of. Given the confined space inside the projector (5x5x9cm) I had to find a cooler that would fit inside this space. A very extensive Google image search made clear that the best option for me was the Nexus NHP-2200 chipset cooler. This one is using heatpipe technology to cool down computer chipsets. It’s made entirely out of copper and it fits the space available while the cooling fins are exactly where I wanted them, in front of the projector’s cooling fan. This cooler is truly a beautiful one, I tried handling it with gloves to avoid fingerprints all over it. The cooler base came a bit oxidized already but that won’t affect its performance, just the overall looks. The tricky part will be to make it cool the LEDs as the PCB I’m using should have been made of metal but I don’t have such technology at my disposal. I’m counting on the projector fans, there are two in front and a big one for the backside of the bulb. Hopefully these will help keeping the temperatures under control.

Initial tests proved the LED array is getting hot really fast, without cooling the array the PCB is too hot to touch in under a minute. The temperature probe on my multimeter reached 70 degrees (Celsius) in a few seconds but this was without the projector fan’s cooling. I have no way of checking the array with the projector’s cooling just yet so I’ll just go ahead with it. Hopefully I won’t fry the LEDs too soon. The Nexus cooler works, it also got warm in a minute but the heat transfer between the array PCB and the cooler’s base was slower than expected. By the time this cooler warms up, the LED array is too hot already. Man I wish I had one of those metal PCBs… The three projector fans should help, at least that’s what I’m hoping.

Step 5: Casing

Believe it or not, to me this was the hardest and most labour-intensive part. As the entire LED conversion should be non-destructive and I had no original bulb at all, I had to replicate as best as I could the original frame and mounting points. There are two mounting screws inside the projector and a few plastic pins to be considered. None of them was in line with the others. Therefore I had to measure all I could measure inside that little space inside the projector and try to make a mock-up of my lamp casing out of cardboard at first, to check the measurements. A few cardboard models later I had all the correct distances. The PCB board I used for this casing is a great material to work with as it’s strong, can be soldered in 90 degrees angle easily and will hold firmly in place all I can put inside that frame. The hardest part was to cut the PCB board into the various shapes needed to assemble the casing. I used a tiny jigsaw and all I can say about that is that it was one painful experience.

Step 6: Light Control

As this array is square in shape I have no way of using a round reflector like the one I used on my v.1.0 lamp. So I’ll make a square one out of thin aluminum sheet. It will also control the light spills as that would disturb the projection experience. A second benefit of this aluminum reflector is that it would also double as a heat sink because its base will touch the LEDs thus taking away some of the generated heat. So it’s more a matter of controlling the light spills than directing the light beam, because, as I mentioned before, the LEDs have a 120 degrees light beam, I have no real way of focusing that too much. Lens are useless here because I have 9 separate light sources spread on a 2x2 cm. Fresnel lens are also not available around here. I was thinking of using tiny CD-ROM lens (from the optical heads) for each LED but those tiny lens have a very short focal distance.

This is where this project got stuck. I made a few attempts to use this lamp in the projector. The light output was bad. I have lights spills all over the place. The light output is blinding but I have no way to control it. The projected image is even weaker thant the one I did with the LED projector lamp v1.0. I blame the beam angle. If I can somehow find a way to efficiently focus this square LED array I believe the end result would be a success. But so far nothing worked. Maybe this forum will help me find the answer and this is why I'm posting this unfinished project. (and to get rid of the ones asking about its status) Ok, I'm just joking.

UPDATE: This LED Light bulb version is cancelled. Due to time restraints and the lack of encouraging results, I'm postponing this project until I can come up with something better. When I do, Instructables will be the first place to read about it, so stay tuned. Meanwhile the v.2.0 version is my new bathroom light. :-) Perfect white and high brightness, it's like a operating room in there.

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41 Discussions

I like your idea for an LED light source mod as it has passed my mind as well to increase lumen output on my Vidikron Model 30.

I think a “light pipe” is what you require to collect and transfer the light through the front end light path. You want to make sure a fan is blowing through that light pipe wether stock or mod fans for something as confined as it will be.I’ve seen treated mirrored rectangle (“Integrators” are the actual technical term) to glass ones in large Xenon projectors. But take note these are on the front end from the light source and traditionaly use an eliptical reflector as the stock Osram lamp would have built onto the traditional lamp. Laser mirror reflector is a good source to look into for material used to make a makeshift integrator/ light pipe.I think anything more is getting into Laser Integrated Projection systems which are quite elaborate and currently large scale and expensive. I would be interested in working on a project scaling down a Laser Integrated projector for home theatre use.

Hey, very interesting projects. I'm thinking of doing it myself and here are the things that I would do differently. Maybe it would get you unstuck:

First off, cooling: LEDs run much cooler than the incandescent bulbs that are usually used in these projectors. Your LEDs run on 22Watts of Power whereas a regular projector bulb can run on up to 200W. The fans of the projector are designed to dissipate 10 times more heat than your LEDs produce, so the whole heat sync assembly is overkill, just line up your LEDs with the air flow of the projector fans and that will keep them nice and cool.

Now onto focusing the light. I was trying to brainstorm how a 120o light can be focus. I drew you a diagram of my idea. Forgive my bad drawing, I'm not a good drawer and I'm getting used to the tablet and the new drawing software. The basic idea here is to have in a little light well or cone made of some reflective material that will redirect the wide angles of the light. You can figure out the angle of the cone mirrors by taking a taking a normal mirror and playing with the angles until you have the light focus you want.

I think this is a great project and even though you may spend something similar to the price of a new bulb, consider that your LEDs will last you 10 to 20 times longer than an incandescent bulb and spend 10 times less electricity. Epson charges 350$US for a new bulb and they rate the bulbs at 4000hrs but alot of people in the forums say that they only last 1000. Your LEDs are rated for 50,000 hours.

The multiple LED lightsources with a single reflector system do create light of course but most of the light will not make it through the projection system. This is due to the so called 'Etendue' of any optical system, the product of the area through which the light traverses or from where it originates and the spatial angle it occupies. A loss-less system can only exist if the source's etendue is equal to or smaller than that of the rest of the optical system. If the etendue of the source is much larger than that of the optical system, most of the light will not be guidable through the system. The projection system has been designed for a high pressure arc lamp that is characterized by an enormous luminance, a light flux emanating from nearly a point, i.e. a very small surface. These lamps have many negatives (short lived, UV, explosion, modest energetic efficiency) but are hard to beat when it comes to their optical geometry, all the light comes from one small point and facilitates an optical system to capture, guide, and image it. The Luminance of a high pressure Mercury arc lamp is in the order of 4 Giga Candela per m2. That of a LED about 8 Mega Candele per m2. A factor of 500 less!

So when it comes to converting electrical energy into light energy without many contraints where that light goes, the LED wins (lumens per Watt) but when it comes to creating light that is useful in a projection system the LED is far inferior.

Conclusion:

Most projection systems are designed such that they operate, even with a high pressure arc lamp, in an etendue situation that is already not lossless.

So the total light emitting surface of the LED should not be bigger than that of the arc in the arc lamp. Assuming for simplicity that the arc is a little sphere with radius 0.5 mm, its surface is 4 * pi * 0.5² = appr. 3 mm².

Unfortunately from such a small surface a LED can only produce a few lumens.

Had this not been the case of course all projectors would have been using LEDs to start with. Latest solid-state trend is the use of laser diodes. They achieve much higher luminances than LEDs can but are costly at the power levels needed.

1) 20k Lumens == 20k Lux == 20k Candellas. 2) The emitter source for the high pressure mercury arc is NOT constrained to 20 degrees, but rather 360- which makes the Candellas without the proper lumiary assembly down to 3k Candellas.3) A similar "proper" lumiary assembly can be made to constrain the LED Emission profile to about 20 degrees.4) With "1", all things being equal, if you constrain the light to 20 degrees of emission profile with low losses, X lumens *DOES* equate to X candela.5) once you get past the 100 lm/watt range, you're in the domains beyond even UHP mercury vapor for luminous intensity.

Now, had you said it was "easier" to accomplish the focusing because of UHP being a point source for the light and the LED's being "more spread out", I'd have bought the statement in spite of the handwavium you're putting out.

However, since you went where you went...I need chest waders for it.

LED's have a potential to be made as good or better with performance levels exceeding 200lm/watt now with the right luminaries. It may or may not be that you can retrofit a projector gracefully with such gear, but it's worth trying. The reason why they have as many "fails" as we seem to have (with a few recent successes, albeit ugly as hell) is that it's harder to get the focusing you need to keep the light going in the right directions for projecting. It's not that it's impossible (you're seeing 800+ lm projectors in that list...)- it's difficult.

Had I known that my instructable would get me CERN-level comments, I would have just posted pictures :-). Thank you for your insights. But we're all beating a dead horse. I gave up on this. I find Xenon bulbs a much better alternative. Not as good as the original, but it does make a projector usable.

That wouldn't make a very interesting instructable. This is a really cool project to me, one might do it to save on lamps, for energy efficiency, just to see if you can, or if you can't get the correct Xenon lamp because it's obsolete, you live in a place where it's not available, or you live in a place where mercury lamps are banned. Or, what if you want to modify the behavior of the projector? Say I'm using one for 3D printing and I want to drop in a UV led, this would be a good starting point. If you don't think making stuff yourself is stupid because you could buy it, why be on instructables?

It is the same story just using the correct lamp instead of LED which have a long way to go to put out the same amount of power. I'd go about with making a universal base with H1 socket mount and provide cooling for it. H1 xenons will be here for a long time and very cheap. I'd also think about using the original ballast from the projector if it's possible. It is about the road not the destination but we also need to chose the right gun for the duck when hunting ducks.

Another thing I thought of, is synchronizing the LED with the shutter, so that you get around twice as much light out and no flicker. Now, the light is mechanically chopped when the shutter advances. A sensor could shut off the LED while the film advances and you could remove the chopper. You wouldn't get any rolling shadow through your movie when you filmed it with a digital camera, would you? At least not if your shutter speed was slow enough.